Hardcore gamer = someone who plays only cinematic grizzed white dude games and/or military fetishizing FPS
Casual gamer = anyone that is not a 15-25 yo male, and/or plays anything outside of the previously mentioned games, especially if those games are colorful.
So basically the gaming community is full of gatekeeping, misogyny, toxic masculinity and general chuddery. They make sure they're the loudest voice heard when anything about games is talked about, and won't be happy until all games a homogenous stream of bland, hyper-realistic but with a grey filter slog of mindless action with no heart or soul. And don't you dare force them to read any dialogue or story.
I only care about DotA.
I don't even know why people put it under the "MOBA" genre really. In my opinion, there is a genre of its own that I would call "Dota-likes" that has basically only ever included DotA, League of Legends and Heroes of Newerth.
MOBA is a stupid genre name, icefrog was correct to push for ARTS as the name.